In recent years, a digital device has been marketed that includes a display unit having a touch panel and allows a user to intuitively execute an operation. A digital device like this generally allows a user to execute a function assigned to a button icon which is provided on a display screen including a touch panel by executing a “tapping” operation on the button icon.
A “tapping” operation on a button icon refers to an operation which can be executed by only momentarily touching the button icon with a user's finger. Immediately after the user's finger is off the button icon, the user operation is input and a function assigned to the button icon is executed.
A size of a body of a digital device having a touch panel has been recently decreased to achieve an advantage such that the total number of parts of physical operation members can be reduced by providing a touch panel. On the other hand, in order to improve the visibility, the size of the touch panel itself has become large.
If a ratio of an area of a touch panel to the size of the entire body of the device becomes large, then a hand of the user holding the device body may involuntarily touch a surface of the touch panel, which may cause an operation error. Various control methods for preventing an operation error of a touch panel have been discussed as follows.
Japanese Patent Application Laid-Open No. 2009-009424 discusses a method in which a touch panel includes an operation inhibited area. When a user touches the operation inhibited area, the control method disables an operation icon or displays a message indicating that the user has executed a wrong operation. Accordingly, the control method allows the user to recognize his/her operation mistake and prevents a wrong setting or an operation error.
Japanese Patent Application Laid-Open No. 05-298027 discusses a method in which if a user continues touching a touch panel at the same location for a predetermined time period, then it is determined that a sensor element for detecting a touching state of the touched position has been malfunctioning. In this case, the method disables an input executed after that by touching the touch panel at the position.
However, because the method discussed in Japanese Patent Application Laid-Open No. 2009-009424 includes the operation inhibited area, a touching operation member, such as an operable button icon, cannot be provided in the operation inhibited area. More specifically, in this control method, a part of the entire area of a touch panel cannot be effectively utilized. In addition, an arrangement and a layout of touching operation members are restricted.
In the method discussed in Japanese Patent Application Laid-Open No. 05-298027, even when a sensor element corresponding to a position touched by the user is normally functioning, if the user has actually touched the touch panel at the same position for a predetermined time period or longer, then it is determined that the sensor element is malfunctioning and the sensor element is disabled. Further, in this case, a touching operation executed after that is disabled. Accordingly, in this control method, a touching operation member, such as a button icon, cannot be provided at the position. More specifically, similar to the case of the method discussed in Japanese Patent Application Laid-Open No. 2009-009424, a part of the entire area of a touch panel cannot be effectively utilized and the arrangement and layout of touching operation members are restricted.